Rochester 2 Jet Choke System

The Rochester 2 Jet carburetor used multiple choke operations.

  • 2G Manual choke – this is easy. A cable leads from the dash to the carburetor choke lever. The choke is manually operated.
  • 2GC Hot air choke – This is also called an integral choke, which means the choke is mounted on the carburetor and a hot air tube is connected from the manifold to the choke. Vacuum inside the choke housing draws the hot air up into the choke heating up the thermostat and opening the choke. The choke illustrated below shows the heat inlet in the center of the choke thermostat. This was how the earlier 2 jets were in the early 50’s. Later the 2 Jet connected the hot air tube to the side of the choke housing. The video illustrates that type.
  • 2GV Divorced choke – The choke thermostat is mounted on the intake manifold with a rod leading up to the choke lever.

2GC Choke
When working with your 2 Jet carburetor make sure your choke parts move freely. Remove all of the choke parts and as you replace them make sure nothing is sticking.

For the integral type (mounted on the carburetor) there is a piston inside the choke housing. You need to remove this and using a wire wheel clean the brass piston. Be careful you don’t lose the small pin that connects the piston to the arm. This will usually be enough for the piston to move freely. This piston is the vacuum break, which when the engine is 1st started and the vacuum is at the highest, opens the choke slightly so that some air is allowed in, otherwise the engine might die. If your engine is dying right after starting and is cold take a look at the vacuum break piston.

Eliminate your choke problems:

2 Jet Electric Choke

Watch a video about this choke:

How the Choke & Fast Idle Works:

Choke linkage example. This is a later model 2 jet with the choke mounted on the throttle body.
2 Jet Choke System, Where the Choke is Mounted on the Throttle Body

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Updated on 12/09/2020

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